#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int fib(int n)
{
	int a = 1;
	int b = 1;
	int c = 1;
	while (n >= 3)
	{
		c = a + b;
		a = b;
		b = c;
		n--;
	}
	return c;
}
int main()
{
	int i;
	while (scanf("%d", &i))
	{
		printf("%d\n", fib(i));
	}
	return 0;
}

